JP6860436B2 - Optical isolator module - Google Patents

Description

The present invention relates to an optical isolator module.

In optical communication and optical measurement, when the light emitted from the semiconductor laser as a light source returns to the semiconductor laser due to reflection from the member surface, fiber end, or lens end provided in the middle of the transmission path, laser oscillation does not occur. It becomes stable. In order to block such reflected return light, an optical isolator using a Faraday rotator that rotates the plane of polarization in a non-reciprocal manner is used (Patent Document 1).

FIG. 13 shows an example of the basic configuration of the polarization-dependent optical isolator. In a polarization-dependent optical isolator, a Faraday rotator 3 is usually arranged between two polarizers (a first polarizer 1 and a second polarizer 2), and a magnet is used to cause the Faraday rotator 3 to move in a traveling direction. It is configured to apply a parallel magnetic field.

When light is incident from the forward direction as shown in FIG. 13A, the incident light is linearly polarized by the first polarizer 1 and passes through the Faraday rotator 3. The incident linearly polarized light is rotated by 45 ° by the Faraday rotator 3 and emitted through a second polarizer 2 provided so that the transmission direction is inclined by 45 ° from the vertical direction.

On the other hand, when light is incident from the opposite direction as shown in FIG. 13B, only the component inclined by 45 ° from the vertical passes through the second polarizing element 2 among the various polarizing components of the return light. This polarized light component receives further 45 ° of optical rotation by the Faraday rotator 3 and becomes polarized light perpendicular to the transmission direction of the first polarizing element 1, so that the light does not return to the light source side.

Japanese Unexamined Patent Publication No. 2011-150208

In recent years, while miniaturization of semiconductor laser modules has been achieved, various polarization treatments are required inside the modules. There is also a demand for processing transmitted light in opposite directions by an adjacent optical isolator, which has not been expected until now.

However, when a plurality of optical isolators are brought close to each other, magnetic field interference due to magnets contained in each optical isolator becomes a problem. This causes factors such as an increase in insertion loss and deterioration of isolation, which makes it impossible to exhibit the original performance of the optical isolator.

The present invention has been made in view of the above problems, and it is possible to prevent performance deterioration such as increase in insertion loss and deterioration of isolation due to magnetic field interference even when a plurality of optical isolators are brought close to each other. It is an object of the present invention to provide a capable optical isolator module.

In order to solve the above problem, in the present invention, a plurality of optical elements including a Faraday rotator and having an optical isolator function when a magnetic field is applied are provided.
A magnet that applies a magnetic field to the Faraday rotator included in the plurality of optical elements, and
Consists of, including
At least two of the plurality of optical elements have optical isolator functions in different directions, and provide an optical isolator module in which the magnetic field directions applied by the magnets are the same.

Such an optical isolator module is an optical isolator module that can prevent performance deterioration such as an increase in insertion loss and isolation deterioration due to magnetic field interference even when a plurality of optical isolators are brought close to each other.

In this case, the optical element is preferably configured to further include a polarizer.

Any optical element configured to include such a polarizer can be suitably used in the optical isolator module of the present invention.

Further, it is preferable that at least two of the plurality of optical elements have an optical isolator function in opposite directions.

Even if the optical isolator module of the present invention is configured to include such an optical element, any of the optical elements can exhibit high performance.

Further, the number of the optical elements can be two.

The configuration of the optical isolator module of the present invention can be suitably used when the number of optical elements is two.

Further, the magnet is preferably a single magnet.

By using such a single magnet, the optical isolator module of the present invention can be easily assembled.

Further, it is preferable that the optical element is fixed on the plane of the flat plate-shaped base, and the polarization direction of the emitted light in the forward direction is parallel to the installation plane of the base.

An optical isolator module including such an optical element can be easily incorporated when used in combination with a waveguide type modulator or the like having an incident polarization direction dependence.

Further, it is preferable that the incident surfaces of the plurality of optical elements are inclined with respect to the surface perpendicular to the light transmission direction, and the inclination directions of the plurality of optical elements are the same.

An optical isolator module having such a configuration and including an optical element can prevent the residual reflection of one optical element from affecting the other optical element.

An optical isolator module as in the present invention can contribute to miniaturization and space saving in a semiconductor laser module or the like, and can perform transmitted light processing in different directions at close positions without performance deterioration due to magnetic field interference.

It is a top view which shows an example of the structure of the optical isolator module of this invention. It is a schematic diagram which shows an example of the transmission polarization direction in the optical element (I) of FIG. It is a schematic diagram which shows an example of the transmission polarization direction in the optical element (II) of FIG. It is a top view which shows another example of the structure of the optical isolator module of this invention. It is a schematic diagram which shows an example of the transmission polarization direction in the optical element (III) of FIG. It is a schematic diagram which shows an example of the transmission polarization direction in the optical element (IV) of FIG. It is a front schematic diagram which shows an example of the structure of the optical isolator module of this invention. It is a front schematic diagram which shows another example of the structure of the optical isolator module of this invention. It is a top view of the optical isolator module of Comparative Example 1. FIG. It is a front schematic diagram of the optical isolator module of Comparative Example 1. It is a schematic diagram which shows the transmission polarization direction in the optical isolator (V) of the comparative example 1. FIG. It is a schematic diagram which shows the transmission polarization direction in the optical isolator (VI) of the comparative example 1. FIG. It is a schematic diagram explaining the structure of the polarization-dependent optical isolator, (a) is a schematic diagram showing the time when light is incident on the polarization-dependent optical isolator from the forward direction, and (b) is the schematic diagram showing the case where light is incident on the polarization-dependent optical isolator from the opposite direction. It is a schematic diagram which shows the time when the light is incident. It is a schematic diagram explaining the structure of the polarization-independent optical isolator, (a) is a schematic diagram showing the time when light is incident on the polarization-independent optical isolator from the forward direction, and (b) is the polarization-independent optical isolator. It is a schematic diagram which shows the time when the light is incident from the opposite direction.

As a result of diligent studies to solve the above problems, the present inventor applies magnetic fields in the same direction to a plurality of optical elements having an optical isolator function when a magnetic field is applied, and each optical element. It has been found that if the directions of the optical isolator functions are different from each other, it is possible to prevent an increase in insertion loss due to magnetic field interference and performance deterioration such as deterioration of isolation, and this invention has been made.

That is, the present invention is configured to include a Faraday rotator and has a plurality of optical elements having an optical isolator function when a magnetic field is applied, and a magnetic field is applied to the Faraday rotator included in the plurality of optical elements. An optical isolator that includes a magnet to be applied, and at least two of the plurality of optical elements have optical isolator functions in different directions from each other, and the magnetic field directions applied by the magnets are the same. It is a module.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

FIG. 1 is a schematic top view showing a configuration example of the optical isolator module of the present invention. Further, FIGS. 7 and 8 show schematic front views showing a configuration example of the optical isolator module of the present invention.

The optical isolator module of the present invention is configured to include a plurality of optical elements having an optical isolator function when a magnetic field is applied. The number of optical elements may be two or more.

The specific configuration of the optical element is not limited, but for example, it is configured to function as a polarization-dependent optical isolator when a magnetic field is applied. In this case, as shown in FIG. 1, the optical elements 101 and 102 are usually configured to include a Faraday rotator 3 and two polarizers (first and second polarizers 2). The Faraday rotator 3 is arranged between the two polarizers. For convenience, the optical element 101 in FIG. 1 is referred to as an optical element (I), and the optical element 102 is referred to as an optical element (II).

Further, when a waveguide type modulator having an incident polarization direction dependence is arranged following the optical isolator, a 1/2 wavelength plate 4 is arranged on the exit side in order to adjust the polarization direction of the emitted light. Any element may be added to the element.

Schematic diagrams showing an example of the transmission and polarization directions of the optical elements (I) and (II) in FIG. 1 are shown in FIGS. 2 and 3, respectively. The bidirectional arrows in FIGS. 2 and 3 schematically show the transmitted polarization direction when the optical element is viewed from the forward direction. The points a to e in FIG. 1 correspond to the points a to e in FIG. 2, and the points f to j in FIG. 1 correspond to the points f to j in FIG. As shown in FIGS. 2 and 3, any of the optical elements of the present invention is configured to transmit light in the forward direction and not to transmit light in the reverse direction.

The optical element may have a 1.5-stage type or a 2-stage type configuration. FIG. 4 shows a schematic top view of a configuration example of the optical isolator module of the present invention including a 1.5-stage optical element, and the optical elements (III) and (IV) in FIG. 4 (in FIG. 4). A schematic diagram showing an example of the transmission polarization direction of the optical element 103 is referred to as an optical element (III) and the optical element 104 is referred to as an optical element (IV) for convenience is shown in FIGS. The bidirectional arrows in FIGS. 5 and 6 schematically indicate the transmitted polarization direction when the optical element is viewed from the forward direction. Points k to q in FIG. 4 correspond to points k to q in FIG. 5, and points r to x in FIG. 4 correspond to points r to x in FIG. The 1.5-stage configuration has a first polarizer 1, a first Faraday rotator 6, a second Faraday rotator 2, a second Faraday rotator 7, and a third polarized light on a light transmission path. It is a configuration in which the children 5 are arranged in this order. Further, the two-stage configuration has a first polarizer, a first Faraday rotator, a second polarizer, a third polarizer, a second Faraday rotator, and a fourth on the light transmission path. It is a configuration in which the polarizers are arranged in this order.

The optical isolator module of the present invention, which includes 1.5-stage or 2-stage optical elements, is preferably used when a tunable laser light source is used or when high isolation is required.

The optical element may be configured to function as a polarization-independent optical isolator when a magnetic field is applied. An example of the basic configuration of the polarization-independent optical isolator is shown in FIG. The polarization-independent optical isolator usually has a configuration in which a Faraday rotator 3 and a 1/2 wave plate 4 are arranged between two birefringent crystals (first birefringent crystal 10 and second birefringent crystal 11). It has become.

When light is incident from the forward direction as shown in FIG. 14A, the incident light is separated into an ordinary ray and an abnormal ray in the polarization direction perpendicular to the ordinary ray by the first birefringent crystal 10. These light rays are rotated by 45 ° by the Faraday rotator 3 and further rotated by 45 ° in the same direction on the 1/2 wavelength plate 4 to enter the second birefringent crystal 11. At this time, since the polarization directions of the normal light rays and the abnormal light rays are exchanged with each other, the separated light is synthesized and emitted when the light is passed through the second birefringent crystal 11.

On the other hand, when light is incident from the opposite direction as shown in FIG. 14B, the return light is separated into an ordinary ray by the second birefringent crystal 11 and an abnormal ray in the polarization direction perpendicular to the ordinary ray. The / 2 wave plate 4 is rotated by 45 °, but the Faraday rotor 3 is rotated by 45 ° in the direction opposite to that of the 1/2 wave plate 4 and is incident on the first birefringent crystal 10. At this time, since the polarization directions of the ordinary light rays and the abnormal light rays are the same as when they are separated by the second birefringent crystal 11, the separation of the two light rays further progresses, and the light does not return to the light source.

Even when the optical element is configured to function as a polarization-independent optical isolator when a magnetic field is applied, a 1.5-stage type or a two-stage type configuration can be adopted.

The material of the Faraday rotator used in the optical element of the present invention is not particularly limited as long as it exhibits a Faraday effect. Examples thereof include bismuth-substituted rare earth iron garnet ((RBi) ₃ Fe ₅ O ₁₂ ), yttrium iron garnet (Y ₃ Fe ₅ O ₁₂ ), terbium gallium garnet (Tb ₃ Ga ₅ O ₁₂ ), and Faraday rotating glass. Since the Faraday rotator can be shortened, a material having a large Faraday rotator coefficient or Verdet constant is preferable.

The type of polarizer used in the optical element of the present invention is not particularly limited, and a polarizing glass, a polarizing beam splitter (PBS), a prism-type splitter using a birefringent crystal, a wire grid-type polarizer, or the like is used. Can be done. Of these, polarized glass is preferable because it can shorten the optical path length.

The elements of the optical element (Faraday rotator, polarizer, 1/2 wave plate, birefringent crystal, etc.) may be fixed via an adhesive or the like. Further, it is preferable to provide an antireflection film corresponding to the adjacent material on the light transmitting surface of each element.

The configurations of the plurality of optical elements included in the optical isolator module of the present invention may be the same or different.

The optical isolator module of the present invention includes a magnet 8 that applies a magnetic field to the Faraday rotators of a plurality of optical elements (see FIGS. 7 and 8). The magnet 8 may use a single magnet or a combination of a plurality of magnets, but the magnetic field directions to be applied must be the same. It is preferable to use a single magnet.

The type of magnet is not particularly limited, and SmCo magnets, Nd-Fe-B magnets, injection molded magnets (bonded magnets) and the like can be used. Of these, SmCo magnets are preferable because they have a high Curie temperature and are resistant to rust. The shape of the magnet is not particularly limited, but it is preferable to use a flat plate magnet for ease of assembly.

The magnet 8 can be arranged at an arbitrary place such as the upper end of the optical element or between the optical elements. For example, as shown in FIG. 7, if the magnet 8 is arranged at the upper end of the optical element, the assembly is very easy. Further, as shown in FIG. 8, if the magnet 8 is arranged between the optical elements, there is an advantage that stray light can be blocked.

In the optical isolator module of the present invention, at least two of the plurality of optical elements have optical isolator functions in different directions. Here, the direction of the optical isolator function refers to the forward direction through which the incident light can be transmitted.

Further, for at least two optical elements among the optical elements, the directions of the optical isolator functions are preferably opposite directions. At this time, if the optical axes of these optical elements are parallel to each other, high performance can be exhibited with respect to a magnetic field in the same direction, which is preferable.

It is preferable that the optical element is fixed on the plane of the flat plate-shaped base 9 as shown in FIGS. 1, 4, 7, and 8. At this time, as shown in FIGS. 2, 3, 5, and 6, it is more preferable that the polarization direction of the emitted light in the forward direction is parallel to the installation plane of the base 9. In this way, when used in combination with a waveguide type modulator or the like having an incident polarization direction dependence, it becomes easy to incorporate.

The material used for the base 9 is not particularly limited, but from the viewpoint of heat dissipation, it is preferable to use a material having high thermal conductivity such as alumina.

Further, as shown in FIGS. 1 and 4, it is preferable that the incident surface of the optical element is inclined with respect to the surface perpendicular to the light transmission direction, and the inclined directions of the incident surfaces of the optical element are the same. The direction is more preferable. At this time, the inclination direction and the inclination angle of the incident surface of each optical element are appropriately selected so as to prevent the influence of the residual reflection of one optical element on the other optical element.

With such an optical isolator module of the present invention, it is possible to prevent performance deterioration such as an increase in insertion loss and isolation deterioration due to magnetic field interference even when a plurality of optical isolators are brought close to each other.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Example 1]
In Example 1, _{an optical isolator module shown in FIG. 1 was produced using a (TbEuBi) 3} (FeGa) ₅ O ₁₂ crystal as a Faraday rotator and a polarizing glass (Polar core manufactured by Corning Inc.) as a polarizer. Further, the transmission polarization directions of the optical elements (I) and (II) are configured to be the transmission polarization directions as shown in FIGS. The detailed manufacturing procedure of the optical isolator module of Example 1 will be described below.

First, 11.0 mm × 11.0 mm × 0.2 mm polarized glass (first polarizer 1) is prepared, and one surface is coated with an anti-aircraft antireflection coating, and the other surface is coated with anti-adhesive. Anti-reflective coating of the agent was applied. Next, a 11.0 mm × 11.0 mm × 0.54 mm Faraday rotator having an anti-adhesive anti-reflective coating on both sides of the anti-adhesive anti-reflection coating of the first polarizing element 1. 3 was bonded via an adhesive.

11.0 mm x 11.0 mm x 0.2 mm polarized glass with anti-adhesive anti-reflection coating on both sides of the Faraday rotator 3 on the side to which the first polarizer 1 is not attached (No. 1 The polarizer 2) of 2 was bonded via an adhesive.

Subsequently, a crystal 1/2 wave plate 4 having an anti-air reflection coating on one surface and an anti-adhesive anti-reflection coating on the other surface was prepared. The surface of the second polarizer 2 to which the Faraday rotator 3 was not bonded was bonded to the surface of the 1/2 wavelength plate 4 to which the antireflection coating of the anti-adhesive was applied, via an adhesive. ..

Then, it was cut into a size of 1.0 mm × 1.0 mm to produce an optical element. Here, the transmission polarization directions of the first polarizer 1 and the second polarizer 2 are set to be relatively different by 45 °.

Two of the produced optical elements were arranged on a flat surface of a flat plate-shaped alumina base 9. At this time, the directions of the optical isolator functions of the two optical elements 101 and 102 are set to be opposite to each other. Further, the incident surfaces of the optical elements 101 and 102 are inclined with respect to the surface perpendicular to the light transmission direction, and the incident surfaces of the optical elements 101 and 102 are inclined in the same direction.

A flat plate-shaped SmCo magnet (magnet 8) was arranged at the upper ends of the two optical elements 101 and 102 to produce an optical isolator module having a surface mount (SMT) configuration as shown in FIG. The Faraday rotator 3 and the strength of the magnetic field were set so that the Faraday rotation angle was 45 ° when light having a wavelength of 1550 nm was transmitted at a temperature of 25 ° C.

As shown in FIGS. 2 and 3, all the optical isolators are configured to transmit light in the forward direction and not to transmit light in the reverse direction. Further, the polarization direction of the emitted light in the forward direction is configured to be parallel to the installation plane of the base 9 by the 1/2 wavelength plate 4.

The insertion loss and isolation of the prepared optical isolator module were evaluated. The forward insertion loss in the optical element (I) 101 was 0.15 dB. Further, in order to evaluate the isolation, after passing through the 1/2 wave plate 4, the transmitted light when polarized light that is in the same direction as the transmitted polarization direction of the second polarizer 2 is incident from the opposite direction. When the insertion loss of was measured, it was 43 dB.

Similarly, when the insertion loss in the forward direction of the optical element (II) 102 was evaluated, it was 0.16 dB. Further, the insertion loss of the transmitted light when the light was incident from the opposite direction was 43 dB.

[Example 2]
In Example 2, the Faraday rotator and the polarizing glass were the same as those used in Example 1, and the optical isolator module shown in FIG. 4 was produced. Further, the transmission polarization directions of the optical elements (III) and (IV) are configured to be the transmission polarization directions as shown in FIGS. 5 and 6, respectively. The detailed production procedure of Example 2 will be described below.

First, 11.0 mm × 11.0 mm × 0.2 mm polarized glass (first polarizer 1) is prepared, and one surface is coated with an anti-aircraft antireflection coating, and the other surface is coated with anti-adhesive. Anti-reflective coating of the agent was applied. Next, a 11.0 mm × 11.0 mm × 0.54 mm (TbEuBi) having an anti-adhesive anti-reflective coating on both sides of the anti-adhesive anti-reflection coating of the first polarizing element 1 (TbEuBi). ₃ (FeGa) ₅ O ₁₂ crystals (first Faraday rotator 6) were bonded together via an adhesive.

Polarized light of 11.0 mm × 11.0 mm × 0.2 mm with anti-adhesive antireflection coating on both sides of the surface of the first Faraday rotator 6 to which the first polarizer 1 is not attached. Glass (second polarizer 2) was bonded via an adhesive.

Subsequently, 11.0 mm × 11.0 mm × 0. The surface of the second polarizer 2 to which the first Faraday rotator 6 is not bonded is coated with an anti-adhesive antireflection coating on both sides. A 54 mm (TbEuBi) ₃ (FeGa) ₅ O ₁₂ crystal (second Faraday rotator 7) was bonded via an adhesive.

Further, the surface of the second Faraday rotator 7 to which the second polarizer 2 is not bonded is coated with an anti-adhesive antireflection coating on both sides of 11.0 mm × 11.0 mm × 0.2 mm. Polarized glass (third polarizing element 5) was bonded to each other via an adhesive.

Next, a crystal 1/2 wave plate 4 having an anti-air reflection coating on one surface and an anti-adhesive anti-reflection coating on the other surface was prepared. The surface of the third polarizer 5 to which the second Faraday rotator 7 is not bonded is coated with the antireflection coating of the 1/2 wavelength plate 4 against the adhesive via an adhesive. I pasted them together.

Then, it was cut into a size of 1.0 mm × 1.0 mm to produce an optical element. Here, the transmission polarization directions of the first polarizer 1 and the second polarizer 2, the second polarizer 2 and the third polarizer 5 are set to be relatively different by 45 °.

Two of the produced optical elements were arranged on a flat surface of a flat plate-shaped alumina base 9. At this time, the directions of the optical isolator functions of the two optical elements 103 and 104 are set to be opposite to each other. Further, the incident surfaces of the optical elements 103 and 104 are inclined with respect to the surface perpendicular to the light transmission direction, and the incident surfaces of the optical elements 103 and 104 are inclined in the same direction.

A flat plate-shaped SmCo magnet (magnet 8) was arranged at the upper ends of the two optical elements 103 and 104 to produce an optical isolator module having a surface mount (SMT) configuration as shown in FIG. The Faraday rotators 6 and 7 and the strength of the magnetic field were set so that the Faraday rotation angle was 45 ° when light having a wavelength of 1550 nm was transmitted at a temperature of 25 ° C.

As shown in FIGS. 5 and 6, each optical isolator is configured to transmit light in the forward direction and not to transmit light in the reverse direction. Further, the polarization direction of the emitted light in the forward direction is configured to be parallel to the installation plane of the base 9 by the 1/2 wavelength plate 4.

The insertion loss and isolation of the prepared optical isolator module were evaluated. The forward insertion loss in the optical element (III) 103 was 0.23 dB. Further, in order to evaluate the isolation, after passing through the 1/2 wave plate 4, the transmitted light when polarized light that is in the same direction as the transmitted polarization direction of the third polarizer 5 is incident from the opposite direction. When the insertion loss of was measured, it was 58 dB.

Similarly, when the insertion loss in the forward direction of the optical element (IV) 104 was evaluated, it was 0.23 dB. Further, the insertion loss of the transmitted light when the light was incident from the opposite direction was 58 dB.

[Comparative Example 1]
In Comparative Example 1, the optical isolator modules shown in FIGS. 9 and 10 were manufactured using the same optical elements as those manufactured in Example 1. One optical element was arranged on the plane of the alumina base 9, and a flat plate-shaped SmCo magnet (magnet 8) was further arranged at the upper end of the optical element to prepare an optical isolator having a surface mount (SMT) configuration. .. In the same manner, two optical isolators were prepared. The Faraday rotator 3 and the strength of the magnetic field were set so that the Faraday rotation angle was 45 ° when light having a wavelength of 1550 nm was transmitted at a temperature of 25 ° C.

The two prepared optical isolators were installed close to each other as shown in the schematic views of FIGS. 9 and 10. Further, FIGS. 11 and 12 show the transmission polarization directions of the optical isolators 105 and 106. For convenience, the optical isolator 105 in FIGS. 9 and 10 is referred to as an optical isolator (V), and the optical isolator 106 is referred to as an optical isolator (VI). The points A to E in FIG. 9 correspond to the points A to E in FIG. 11, and the points F to J in FIG. 9 correspond to the points F to J in FIG. Each optical isolator is configured to transmit light in the forward direction and not to transmit light in the reverse direction. Further, the emission light in the forward direction is configured so that the polarization direction is parallel to the installation plane of the base 9 by the 1/2 wavelength plate 4. The magnetic field direction of the optical isolator (V) 105 by the magnet 8 and the magnetic field direction of the optical isolator (VI) 106 by the magnet 8 are configured to be opposite to each other.

The insertion loss and isolation of the optical isolator of Comparative Example 1 were evaluated. The forward insertion loss in the optical isolator (V) 105 was 0.34 dB. Further, in order to evaluate the isolation, after passing through the 1/2 wave plate 4, the transmitted light when polarized light that is in the same direction as the transmitted polarization direction of the second polarizer 2 is incident from the opposite direction. When the insertion loss of was measured, it was 24 dB.

Similarly, when the forward insertion loss in the optical isolator (VI) 106 was evaluated, it was 0.36 dB. Further, the insertion loss of the transmitted light when the light was incident from the opposite direction was 22 dB.

From the above Examples 1 and 2, it was found that the optical isolator module of the present invention is good because the magnetic field direction of the magnet 8 is the same, so that the insertion loss and the deterioration of the isolation are small. On the other hand, in the two close optical isolators of Comparative Example 1, since the magnetic fields generated by the magnets 8 of each optical isolator interfere with each other, the insertion loss increases and the isolation deteriorates as compared with the optical isolator module of the present invention. I understood it.

From the above, it has been clarified that according to the present invention, it is possible to prevent performance deterioration such as increase in insertion loss and isolation deterioration due to magnetic field interference even when a plurality of optical isolators are brought close to each other. ..

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any object having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect and effect is the present invention. Is included in the technical scope of.

1 ... 1st polarizer, 2 ... 2nd polarizer, 3 ... Faraday rotator,
4 ... 1/2 wave plate, 5 ... 3rd polarizer, 6 ... 1st Faraday rotator,
7 ... 2nd Faraday rotator, 8 ... Magnet, 9 ... Flat plate base,
10 ... 1st birefringent crystal, 11 ... 2nd birefringent crystal,
101 ... Optical element (I), 102 ... Optical element (II),
103 ... Optical element (III), 104 ... Optical element (IV),
105 ... Optical isolator (V), 106 ... Optical isolator (VI).

Claims (5)

A plurality of optical elements including a Faraday rotator and having an optical isolator function when a magnetic field is applied.
A magnet that applies a magnetic field to the Faraday rotator included in the plurality of optical elements, and
Consists of, including
At least two of the plurality of optical elements are arranged in parallel, have optical isolator functions in different directions, and have the same magnetic field direction applied by the magnet.
The optical element is fixed on the plane of the flat base, and the polarization direction of the emitted light in the forward direction is parallel to the installation plane of the base.
The magnet is a single magnet der flat plate shape is, top or an optical isolator module to der characterized Rukoto those disposed between the plurality of optical elements of the optical element. The optical isolator module according to claim 1, wherein the optical element is configured to further include a polarizer. The optical isolator module according to claim 1 or 2, wherein at least two of the plurality of optical elements have optical isolator functions in opposite directions. The optical isolator module according to any one of claims 1 to 3, wherein the number of the optical elements is two. The incident surface of the plurality of optical elements is inclined with respect to a surface perpendicular to the light transmission direction, and the inclined directions of the plurality of optical elements are the same. The optical isolator module according to any one of items 1 to 4.

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